1. Field of the Invention
The present invention relates to electrical signal routing apparatus and, more particularly, to apparatus for routing a control signal.
2. Description of Related Art
An electrical contactor is an electrically controlled switch used for selectively providing electrical power to one or more load devices. Contactors are used to control electric motors, lighting, heating, capacitor banks, thermal evaporators, and other electrical loads. A typical electrical contactor has control terminals for connecting to a magnetic coil, line terminals for connecting to conductors providing electrical power (i.e., line conductors), and load terminals for connecting to one or more load devices.
Larger heating, ventilating, and air conditioning (HVAC) systems usually include separate “high side” and “low side” units. The high side units are typically located outdoors, and include a compressor, a condenser coil, and a condenser fan. The low side units are typically located indoors, and include an evaporator coil and an evaporator fan. High side units typically include electrical contactors that supply electrical power to the compressor and the condenser fan motor in response to a control signal.
On high side units the control signal may be provided directly to the electrical contactor, or routed through one or more pressure and/or temperature switches. FIGS. 1A-1C illustrate some of ways the control signal may be routed. FIGS. 1A-1C show top plan views of a typical contactor 10 including line-side terminals 12A and 12B, load-side terminals 14A and 14B, a magnetic coil 16, and quick connect control signal terminals 18A and 18B connected to the magnetic coil 16. When an electrical current “I” flows through the magnetic coil 16, the contactor 10 is energized, the load-side terminal 14A is connected to the line-side terminal 12A, and the load-side terminal 14B is connected to the line-side terminal 12B.
FIG. 1A illustrates how a control signal may be routed directly to the control signal terminals of the contactor 10. The quick connect control signal terminal 18A is connected to a common connection “C,” and the quick connect control signal terminal 18B is connected to an electrical voltage “Y” (e.g., from a thermostat). The electrical voltage “Y” formed between the quick connect control signal terminals 18A and 18B is the control signal. When the voltage “Y” is sufficient, the current “I” flows through the magnetic coil 16, and the contactor 10 is energized.
FIG. 1B illustrates how the control signal may be routed to the control signal terminals of the contactor 10 through a high pressure switch 20. The control signal terminal 18A is connected to the common connection “C,” and the control signal terminal 18B is connected to the voltage “Y” via the high pressure switch 20 (shown in the closed position). The contactor 10 is energized when the voltage “Y” is sufficient and the high pressure switch 20 is in the closed position.
FIG. 1C illustrates how the control signal may be routed to the control signal terminals of the contactor 10 through the high pressure switch 20 and a low pressure switch 22. The control signal terminal 18A is connected to the common connection “C” via the low pressure switch 22 (shown in the closed position), and the control signal terminal 18B is connected to the voltage “Y” via the high pressure switch 20 (shown in the closed position). The contactor 10 is energized when the voltage “Y” is sufficient and the high pressure switch 20 is in the closed position and the low pressure switch 22 is in the closed position.
A problem arises in that the control signal is routed through different pressure switches on different systems, and the routing of the control signal is typically accomplished via electrical connections made by hand. If a wiring error is made when routing the control signal, such as during original system assembly or subsequent system repair, the wiring error may result in injury to a technician performing the work, damage to the contactor or one or more of the load devices, and/or create an unsafe operating condition.